Refactoring testDragIcon() test

- refactoring getWidget method to add support for different app packages.
 - removing platinum test annotation since adding test on platform scenario test.

Test: Presubmit, Local
Bug: 303258153
Flag: NONE
Change-Id: Ifd5e50cfe8019984ba25312f52266e8b1774318e

tests/src/com/android/launcher3/ui/widget/TaplAddWidgetTest.java

@@ -47,7 +47,6 @@ public class TaplAddWidgetTest extends AbstractLauncherUiTest {
     @Rule
     public ShellCommandRule mGrantWidgetRule = ShellCommandRule.grantWidgetBind();
 
-    @PlatinumTest(focusArea = "launcher")
     @Test
     @PortraitLandscape
     @ScreenRecordRule.ScreenRecord // b/289161193